/*
 * Copyright (C) 2006-2010 Alfresco Software Limited.
 *
 * This file is part of Alfresco
 *
 * Alfresco is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * Alfresco is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with Alfresco. If not, see <http://www.gnu.org/licenses/>.
 */

package org.alfresco.jlan.smb.dcerpc;

import org.alfresco.jlan.util.DataPacker;

/**
 * DCE Data Packer Class
 *
 * <p>Contains static methods for packing/unpacking different data types into a byte buffer.
 *
 * @author gkspencer
 */
public class DCEDataPacker {

	/**
	 * Unpack a DCE string from the buffer
	 *
	 * @param buf byte[]
	 * @param off int
	 * @return String
   * @exception  java.lang.IndexOutOfBoundsException   If there is not enough data in the buffer.
   */
	public final static String getDCEString(byte[] buf, int off)
		throws IndexOutOfBoundsException {

		//	Check if the buffer is big enough to hold the String header

		if ( buf.length < off+12)
			throw new IndexOutOfBoundsException();

		//	Get the maximum and actual string length

		int maxLen = DataPacker.getIntelInt(buf,off);
		int strLen = DataPacker.getIntelInt(buf,off+8);

		//	Read the Unicode string

		return DataPacker.getUnicodeString(buf,off+12,strLen);
	}

	/**
	 * Pack a DCE string into the buffer
	 *
	 * @param buf byte[]
	 * @param off int
	 * @param str String
	 * @param incNul boolean
	 * @return int
	 */
	public final static int putDCEString(byte[] buf, int off, String str, boolean incNul) {

	  //	Pack the string header

	  DataPacker.putIntelInt(str.length() + 1,buf,off);
	  DataPacker.putZeros(buf,off+4,4);

	  if ( incNul == false)
	  	DataPacker.putIntelInt(str.length(), buf, off+8);
	  else
	  	DataPacker.putIntelInt(str.length() + 1, buf, off+8);

	  //	Pack the string

	 	return DataPacker.putUnicodeString(str,buf,off+12,incNul);
	}

	/**
	 * Align a buffer offset on a longword boundary
	 *
	 * @param pos int
	 * @return int
	 */
	public final static int wordAlign(int pos) {
	  return ( pos + 1) & 0xFFFFFFFE;
	}

	/**
	 * Align a buffer offset on a longword boundary
	 *
	 * @param pos int
	 * @return int
	 */
	public final static int longwordAlign(int pos) {
	  return ( pos + 3) & 0xFFFFFFFC;
	}
}
